Advances in plasma processing have provided for the growth in the semiconductor industry. In plasma processing, a gas distribution arrangement may be utilized to pump process gases into a plasma processing system. Gas distribution systems interact with power sources, such as microwaves, to generate plasma used in substrate processing.
Gas distribution arrangement may include a gas inlet, from which process gases (e.g., O2, N2, N2:H2, He:H2, water vapor, fluorinated compounds, etc.) may be dispatched. Process gas flow may typically be directed to the center of a plasma tube. In some examples, the diameter of a conventional gas inlet may generally be narrower than a conventional plasma tube. In an example, conventional gas inlet diameter may measure approximately 0.25 inches to 0.50 inches, whereas a conventional plasma tube diameter may measure approximately 1 inch. To facilitate discussion, FIG. 1 shows a simple diagram of a plasma source with a gas inlet. Gas inlet 102 may dispatch one or more process gases into plasma tube 104. Process gases may travel down through the center of plasma tube 104 and interact with the power source within ignition zone 106 to form plasma 108. Because of differences in diameter between gas inlet 102 and plasma tube 104, process gases may not be able to sufficiently fill out the ignition zone 106 of plasma tube 104 to allow for a high rate of interaction with the power source.
In addition, heat influx from the interaction may traverse back beyond ignition zone 106 toward gas inlet 102 to attack o-rings 112 and 114. Generally, coolant may flow through a cooling arrangement 110, which may enclose a large portion of plasma tube 104, to reduce the thermal loading that may occur in plasma tube 104. However, in some examples, o-rings 112 and 114 may be coupled directly to plasma tube 104 without a direct cooling arrangement. Consequently, heat influx from the plasma may flow through plasma tube 104 and may heat up adjacent o-rings 112 and 114. Because o-rings are poor conductor of heat, o-rings 112 and 114 may absorb the influx heat, thereby resulting in the destruction of o-rings 112 and 114. To prolong the life of o-rings, operators may cycle process intervals (i.e., power down the system for a time) to allow time for o-rings to cool. Consequently, average substrate processing time may become relatively long in comparison to actual processing time.
To provide some protection to o-rings, a gas inlet may be enclosed within a plug. FIG. 2 shows a cross-sectional view of a plug gas inlet. A plug gas inlet 202 may be configured to include a gas inlet 206 from a gas inlet end cap 208 to a plug end 210. Once inserted into plasma tube 204, plug end 210 may be disposed downstream from an area of plasma tube 204 shielding o-rings 212 and 214. When process gases are introduced through gas inlet 206, o-rings 212 and 214 may be protected by the plug design since heat influx traversing back toward o-rings may be unable to bypass the inserted plug gas inlet 202. However, the configuration of plug gas inlet still does not provide a mechanism for more effective distribution of process gases within ignition zone of plasma tube 204.
Given the need to stay competitive, a gas distribution arrangement is needed that is capable of evenly distributing the process gases into an ignition zone while also providing protection to the vulnerable o-rings.